<?php
echo pow(3,2) . "\n"; // 3的2次方
echo sqrt(2) . "\n";
echo round(3.6458, 1) . "\n"; //保留1位小数
echo round(3.6458, 2) . "\n"; //保留2位小数
echo cos(60*pi()/180) . "\n"; //cos 的单位是弧度
echo cos(deg2rad(60)) . "\n"; //cos 的单位是弧度